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Lesson 9 Deleting triggers
Objective Practice deleting triggers.

Required Steps to Delete SQL-Server Triggers

How do I delete triggers in SQL-Server 2022 when the business rule defined by the trigger is no longer required?
To delete a trigger in SQL Server when the business rule it enforces is no longer required, you can use the `DROP TRIGGER` statement. This statement removes the specified trigger from the database, so it's important to be sure that the trigger is no longer needed before dropping it. Here's how you can do it: ### Syntax for Dropping a Trigger ```sql DROP TRIGGER [ IF EXISTS ] { [ schema_name . ] trigger_name } [ ,...n ] [ ; ] ``` - `DROP TRIGGER`: This is the command used to delete a trigger. - `IF EXISTS`: This is an optional clause that checks if the trigger exists before attempting to drop it, which helps avoid errors in case the trigger does not exist. (This option is available from SQL Server 2016 (13.x) onwards.) - `schema_name`: The name of the schema to which the trigger belongs. This is optional if the trigger is in the default schema for the database user. - `trigger_name`: The name of the trigger you want to drop. - `,...n`: Indicates that you can drop multiple triggers in a single statement by separating their names with commas. ### Example 1: Dropping a Single Trigger If you have a trigger named `trgDelete` on a table, and you want to remove it, the SQL statement would look like this: ```sql DROP TRIGGER trgDelete; ``` ### Example 2: Dropping a Trigger with Schema Name If the trigger is under a specific schema, you should include the schema name: ```sql DROP TRIGGER schema_name.trgDelete; ``` ### Example 3: Using IF EXISTS to Avoid Errors To prevent errors if the trigger does not exist, use the `IF EXISTS` clause: ```sql DROP TRIGGER IF EXISTS trgDelete; ``` ### Considerations - **Permissions**: Ensure that you have the necessary permissions to drop triggers in the database. Typically, you need to be the trigger owner, have `ALTER` permission on the table or view on which the trigger is defined, or be a member of a role with the required permissions (e.g., `db_ddladmin` or `db_owner`). - **Impact Analysis**: Before dropping a trigger, consider the impact on the database and applications. Ensure that the business rule enforced by the trigger is genuinely no longer required and that dropping it will not lead to data integrity issues or unwanted behavior. - **Backup**: It's a good practice to back up the trigger definition (by scripting it out) before dropping it, in case it needs to be reinstated later. After executing the `DROP TRIGGER` statement, the trigger will be removed from the database, and the actions it was designed to perform will no longer occur in response to data modifications.
There may come a time when the business rule defined by the trigger is no longer in place. Therefore, to stop enforcement of the rules, you must delete the trigger.
To use Enterprise Manager:
  1. Right-click the name of the table that the trigger is assigned to.
  2. Choose the All Tasks | Manage Triggers menu option, and select your trigger from the drop-down list.
  3. Click the Delete button to delete your trigger.

Using Transact-SQL

To delete a trigger with Transact-SQL, you will use the DROP TRIGGER statement, as shown below:

Using the DROP TRIGGER statement
Using the DROP TRIGGER statement

To delete a trigger named trgSalary, simply execute this Transact-SQL statement:

In the next lesson, you will learn how to test triggers.
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